Esters of n-cyanoalkyl-n-alkylphosphoramidic acids



Feb. 13, 1968 E. s. BLAKE ETAL 3,369,061

ESTERS OF NCYANCALKYL-N-ALKYLPHdSPHORAMIDIC ACIDS Filed Oct. 9, 1964' FIGURE l FORCE FIGURE 2 II I INVENTORS.

EDWARD s. BLAKE RALPH E.De.BRUNNER BY JAMES A.WEBSTER ATTORNEY United States Patent lice 3,369,061 ESTERS F N-CYANOALKYL-N-ALKYL- PHOSPHORAMIDIC ACIDS Edward S. Blake, Ralph E. De Brunuer, and James A. Webster, Dayton, Ohio, assignors to Monsanto Research Corporation, St. Louis, Mo., a corporation of Delaware Filed Oct. 9, 1964, Ser. No. 402,819 Claims. (Cl. 260--940) ABSTRACT OF THE DISCLOSURE Compounds of the formula 0 Y T I ROP-NTCN R-O in which R and R are fluorine-substituted alkyl or alk aryl radicals (R' may also be aryl), Y is alkyl and T is alkylene, said compounds being esters of N-cyanoalkyl-N-alkylphosphorarm'dic acids, and being useful as hydraulic fluids.

This invention relates to organic phosphoramidates and more particularly provides a new and valuable class of phosporamidates, the method of preparing the same, functional fluids comprising the new *amidates and hydraulic pressure devices and methods of actuating such devices in which said fluids are used.

According to the invention there are provided esters of N-cyanoalkyl-N- alkylphosphorarnidic acids by the reaction of certain phosphorohalid-ates with certain (alkylamino)alkanenitriles, substantially according to the scheme:

in which R is selected from the class consisting of fluorinesubstituted alkyl radicals of the formula where A is selected from the class consisting of hydrogen and fluorine, m is 0 to 7 and n is 1 to 4, and (perfluoroalkyl)pe:nyl radicals of from 7 to 10 carbon atoms, R is selected from the class consisting of R and aromatic hydrocarbon radicals which are free of olefinic and acetylenic unsaturation and contain from 6 to 12 carbon atoms, X is halogen having anatomic weight greater than 34, Y is an alkyl radical of from 1 to 4 carbon atoms, and T is a bivalent Ialkylene radical of from 1 to 4 carbon atoms.

Examples of (alkylamino) alkanenitriles which react with the phosphoroh'alidates to give the presently provided esters of N-cyanoalkyl-N-alkylphosphoramidic acids are the N-alkylglycinonitriles such as N-methylor N-propylglycinonitrile; the 2-(alkylamino)propionitriles such as 2-(butylor methylamino)propionitrile; the 3-(lalkylamino)propionitriles such as 3-(ethyl-, methyl-, propyl-, or butylamino)propionit1iles; the 2-(alkyl-a'rnino-) butyronitriles such as 2-(methylamino)butyronitrile; the 2-(alkyl- 2-(methylamino)butyronitriles such as Z-methyI-Z-(methylarnino)butyronitrile; the 3-(alkylamino)butyronitriles such as 3-(butylor ethylamino)butyronitrile; the 2-(a1kylamino)valeronitriles such as Z-(methylor propylamino)valerom'trile; the 5-( alkylamino)valeronitriles such as S-(butylor ethylamino)valeronitrile, etc.

One class of compounds which are provided by this 3,369,061 Patented Feb. '13, 1968 invention are the bis(fluorine-substituted lalkyDN-alkyl- N-(cyano-alkyl)phosphonamidates which are depicted by the formula 0 Y [AOF(CF2)m(CHz)D-O]zJT I ITCN where A, m and n areas defined above. This class of compounds is readily prepared by the reaction of an appropriate bis(fluorine-substituted alkyl) phosphorohalid'ate with an (alkylamino) alkanenitrile. Examples of such suitable phosphorohalidates include the simple esters of phosphorohalidic acids such as bis(2,2-difluoroethyl), bis(2,2,2- trifluoroethyl), Ibis (3,3,3-trifluoropropyl), bis (2,2,3,3,4,4, 4-heptafluorobutyl) bis( 3 ,3,4,4,5 ,5 -hexafluoropentyl) bis- (2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl bis(5,5,6,6,7,7, 8,8,9,9-decafluorononyl), bis(2,2,3,3,4,4,5,5,6,6-undecafluorohexyl, or bis(5,5,6,6,7,7,8,8,9,9,10,10,10-tridccafluorodecyl)phosphorochlorid'ate or phosphorobromidate or phosphoriodidate; as well as the mixed esters such as 3,3,3- trifluoropropyl 2,2-difluoroethyl phosphorochlorid'ate or phosphorobromidate or 2,2,3,3,4,4,5,5-octafluoropentyl 3,3,4,4-pentafluorobutyl phosphor'ochloridate or phosphoriodidate.

Another class of presently provided compounds are the bis(perfluoroalkylphenyl) N-alkyl-N-cyanoalkylphosphora'midates of the formula wherein Z denotes a perfluoroalkyl radical of from 1 to 4 carbon atoms and Y and T are as defined above. This class of compounds is easily obtained by the reaction of a bis(perfluoroalkylphenyl) phosphorochalidate with tan (alkylamino)alkanenitrile. Examples of phosphorohalidates which are useful for this purpose are bis(o-, mor p trifluoromethylphenyl)phosphorochloridate, phosphorobromidate or phosphoroiodidate, bis(o-, mor peperfluoroethylphenyl)phosphorochloridate or phosphorobromidate, bis(o-, 'mor p-perfluoropropylphenyl)phosphorobrornidate or phosphoriodidate, bis(o-, mor p-perfluorobutylhenyl) phosphorochloridate or phospborobromidate, etc. Still another class of presently provided compounds are the mixed esters, i.e., the fluorine-substituted alkyl perfluoroalkylphenyl N-alkyl-N (cyanoalkyl)phosphoramidates of the formula 0 Y ;1 IICN wherein Z, A, Y, T, m and n are as defined above. They are readily prepared, according to the invention, by the reaction of an appropriate fluorine-substituted alkyl (perfluoroalkylphenyl)phosphorohalidate with an (alkylamino)alkanenitrile. Examples of such phosphorohalidates are 2,2,3,3,4,4,5,5-oct'afluoropentyl m-trifluoromethylphenyl phosphorochloridate or phosphorobromidate or ph'osphoriodidate; 4,4,4-trifluorobutyl o-trifluoromethylphenyl phosphorochloridate or phosphorobromidate; 2,2-difluoroethyl m-perfluoroethylphenyl phosphorochloridate or phosphoriodidate; 2,2,3,3,4,4,4-heptafluorobutyl m-perfluorobutylphenyl phosphorochloridate or phosphorobromidate, etc.

Another class of the presently provided compounds are mixed esters of the N-cyanoalkyl-N-phosphoramidic acids in which one ester group is derived from a hydrocarbon phenol and the other ester group is derived from a perthe alkane portion of the (alkylamino)alkanenitrile which is condensed with the phosphorohalidate. In the table, the symbol denotes phenyl.

fluoroalkyl-substituted phenol, i.e., compounds of the formula wherein Z, Y and T denote the hereinbefore defined perfiuoroalkyl, alkyl and alkylene radicals, respectively, and aryl denotes an aromatic hydrocarbon radical which is free of olefinic and acetylenic unsaturation and contains from 6 to 12 carbon atoms. This class of compounds is obtained, according to the invention, by the reaction of a (perfiuoroalkyl)phenyl aryl (or .alkaryl or aralkyl)phosphorohalidate with an (alkylamino)alkanenitrile. Examples of suitable phosphorohalidates include o-, mor p-trifiuoromethylphenyl phenyl phosphorochloridate phosphorobromidate or phosphoriodidate; mor p-trifluoromethylphenyl o-, mor p-tolyl phosphorochloridate or phosphorobromidate; o-, mor p-perfluoroethylphenyl benzyl phosphorochl-oridate or phosphoriodidate; 0-, mor p-perfluorobutylphenyl ozor B-naphthylphosphorochloridate or phosphorobrornidate, o-, mor p-biphenylyl 0-, mor p-trifluoromethylphenyl phosphorochloridate or phosphorobromidate, o-, mor p-cyclohexylphenyl o-, mor p-perfluoroethylphenyl phosphorochloridate, etc.

Another class of mixed esters of N-cyanoalkyl-N-alkyl consists of compounds in which one ester group is derived from a hydrocarbon phenol and the other ester group is derived from an appropriate fluorine-substituted alcohol. Such compounds have the formula.

wherein A, m, n, aryl, Y, and T are as defined above. Examples of phosphorohalidates which are useful for preparing this class of compounds are 2,2,3,3-tetrafiuo-robutyl phenyl phosphorochloridate or phosphorobromidate; 2,2,3,3,4,4,5,S-octafluoropentyl 0-, mor p-ethylphenyl phosphorochloridate or phosphoriodidate; 3,3,3-trifluoropropyl o-, morp-hexylphenyl phosphorochloridate or phosphorobromidate, 2,2,3,3,4,4,5,5,6,6 decafluorohexyl Reaction of the phosphorohalidate with the (alkylamino)alkanenitrile takes place by simply contacting the halide with the nitrile at ambient temperature or with heating. In some instances, the reaction rate is accelerated by heating; and, particularly when working with the higher molecular weight phosphorohalidates, temperatures of from, say, 50 C. to below the decomposition temperature of either the reactants or the amidate product are employed. The reaction may be slightly exothermic; so that for smooth reaction, extraneous cooling may be desirable. Generally, depending upon the nature of the individual reactants, temperatures of from, say, 0 C. to 100 C., and preferably of from, about 15 C. to C. are useful.

The reaction may or may not 'be conducted in the presence of an inert, organic liquid diluent or solvent, e.g., a halogenated alkent such as chloroform, carbon tetrachloride or ethylene chloride; an ether such as ethyl ether, dioxane or diethylene glycol dimethyl ether; an amide such as dimethylformamide or dimethylacetamide, etc,

A catalyst may or may not 'be used. Operation may be conducted in the presence of a basic agent to serve as scavenger for the by-product hydrogen halide. The basic agent may be inorganic or organic, e.g., it may be a tertiary alkylamine such as triethylamine or tributylamine; a heterocyclic nitrogen base such as N-methylmorpholine or pyridine; an alkali or alkaline earth metal oxide or the basic salt thereof such as sodium, potassium, lithium, calcium or magnesium oxide, carbonate or acetate, etc.

All of the reaction conditions, i.e., whether or not a diluent and/ or basic agent is employed and the nature of the diluent or of said agent if it is used, temperature, pressure, reaction time, reactant proportions, etc., can be readily arrived at by easy experimentation. Thus arrival at optimum reaction conditions is simply a matter of routine procedure by one skilled in the art. Reaction is generally rapid and is usually evidenced by precipitation of amine hydrohalide. To assure complete reaction in experimental runs, it is generally recommended that after initial reaction has appeared to subside, the reaction mixture be allowed to stand at room temperature for a time before working up the product or that the temperature of the reaction mixture be increased after sufficient time has elapsed for any exothermic reaction to have occurred.

As has already been pointed out, formation of the presently provided N-alkyl-N-(cyanoalkyl)phosphoramidates takes place by condensation of one mole of the fluorinecontaining diorgano phosphorohalidate with one mole of the (aminoalkyl)alkanenitrile. Hence the reactants are advantageously employed in such stoichiometric proportions. However, an excess of either reactant may be employed, and such excess is recommended when it is desired to assure complete reaction of a comparatively more difliculty synthesized halidate or nitrile. Any excess reactant is readily recovered from the final reaction mixture, e.g., by distillation. When a basic scavenger is used, the phosphoroamidate product is conveniently isolated from the reaction mixture by first removing the hydrohalide by-product, e.g., through water-washing, and then fractionally distilling the residual organic phase in order to remove any unreacted reactant, organic base, diluent, etc., that may be present.

The presently provided N-alkyl-N-(cyanoalkyl)-phosphoramidates are stable, well characterized, normally liquid materials. They are of particular interest for use as functional fluids, since they are generally fluid over wide temperature ranges, possess high flash points and high ignition points, and are characterized by very good thermal stability. The compounds remain liquid at low temperatures as well as at temperatures which are substantially higher than 400 F. Hence they are eminently suited for use as hydraulic fluids, especially in hydraulic systems which are subjected to widely varying temperature con ditions. The present compounds possess good viscosity/ temperature relationships and are also useful, e.g., as heatexchange media, gyro fluids, and lubricants.

Evaluation of the hydraulic fluid eflicacy of the presently provided phosphoramidates was conducted by determining such characteristics as pour point, kinematic viscosity, autogenous ignition temperature and behavior upon suddent exposure to very high temperatures. The following procedures were used to obtain the data given in the working examples which follow:

The pour point was determined by American Society for Testing Materials (hereinafter referred to as ASTM) procedure D97-57, except that a small pour point tube, Model J-2436 supplied by Scientific Glass Apparatus Company was substituted for the larger tube prescribed in said ASTM procedure. This was done to conserve test material.

Kinematic viscosity was determined by ASTM D-445-T 1961 procedure, using Cannon-Manning Semi-Micro viscometers calibrated and supplied by the Scientific Development Corporation, State College, Pa.

The flash points and fire points were determined by ASTM D92-57 procedure, modified for testing 1 ml. samples.

The autogenous ignition temperature was determined by ASTM D2155-63T procedure.

Flammability at 1300 F. was determined by visual observation of the behavior of the test material when introduced dropwise at the surface of molten aluminum which is maintained at 1300 F. If no burning resulted, a single spark was applied for a more stringent test of fire resistance.

Owing to the very good physical properties of the present fluorine-containing esters of N-alkyl-N-(cyanoalkyl)phosphoramidic acids, the invention provides improved hydraulic systems wherein said compounds are employed as the operative fluid. Such systems comprise a displaceable member and a displacing force which is transmitted to said member by means of said fluid, as shown in the schematic diagrams of FIGURE 1 of the drawings. Here, a displacing force is applied to piston 1 and transmitted through the fluid 2 contained in cylinder 3 whence it travels through line 4 into cylinder 5 where it acts on the displaceable member 6. In such a system, actuation of a movable member by the presently provided fluid gives performance characteristics which are outstanding because of the physical properties of the fluid.

'While hydraulic systems will contain such elements as pumps, valves, cylinders and pistons, the efiicacy of the system necessarily depends upon the fluid, since the fluid must be one which can withstand pressure and remain fluid under the conditions of use. FIGURE 2 of the drawings is a schematic diagram which well illustrates the indispensable role of the fluid in cooperation with other components of a hydraulic system. Here the fluid is store-d in reservoir 21, and is pumped therefrom by means of pump 22 and through the directional control valve 23 into either end of cylinder 24, where it acts on piston 25 connected by shaft 26 to a motor (not shown) or other device which converts the hydraulic pressure applied to piston 25 into mechanical energy. Action of the fluid on piston 25 displaces the piston until it reaches the end of its travel. The piston may be caused to travel in either direction by adjustment of the direction valve 23. Valve 23 provides for return of the fluid from the opposite side of the piston, back to reservoir 21. Relief valve 28 is provided to maintain a constant hydraulic pressure within the system. When a predetermined pressure is reached, the fluid will flow back to reservoir 21 by functioning of said relief valve.

Owing to their good fire-retardant properties, the fluorine-containing esters of the N-alkyl-N-cyanoalkylphosphoramidic acids are particularly useful in hydraulic pressure devices that are employed under conditions wherein any leak or break in the hydraulic system could provide great danger from fire. The viscosity characteristics and ASTM slopes of the fluids make them of great utility for the transmission of powder in a hydraulic system having a pump therein which supplies power for the system, e.g., in a fluid motor comprising a constantor variable-discharge piston pump which is caused to rotate by the pressure of the hydraulic fluid of the system. The present fluid likewise serves to lubricate the frictional, moving parts of such hydraulic systems.

For use in a conventional automatic transmission, the presently provided hydraulic fluid is contained in the outer casing of the transmission device, which casing is attached to the usual engine crankshaft and flywheel and rotates therewith. Within the fluid is a coupling comprising an impeller connected to said casing and a turbine which is connected to the drive shaft'of the vehicle. The turbine is driven by the motion of the fluid in response to the rotation of the impeller, as the casing to which the impeller is attached is actuated by the crankshaft and flywheel.

The presently described N-alkyl-N-(cyanoalkyl)phosphoramidates are particularly suited for use as the operative fluids in hydraulic braking devices owing to their very good vapor pressure characteristics. Under current, severe operating conditions heat build-up, within the brake system is frequently encountered. Unless the fluid remains liquid at the high temperatures thus developed, the hydraulic brake system becomes inoperable since the vaporized fluid becomes compressible. Although much effort has been expended at providing high boiling hydraulic brake fluids, generally materials which are high boiling congeal at low temperatures.

The presently provided fluids have boiling points which are well over 400 F. and some of them do not boil until over 600 F. Hence hydraulic brake systems in which these fluids are used withstand the dangers ensuing from heat build-up. At the same time, owing to the low pour points of the fluids, the system is one which is operable in very cold environment. The present invention thus provides an improved method for applying pressure to a hydraulic brake through a fluid.

The presently provided compounds and mixtures are useful as the hydraulic fluids of hydraulic machines,

generally, e.g., lifts, hoists, jacks, lockgates, presses, etc.

The invention is further illustrated by, but not limited to, the following examples:

Example 1 A mixture consisting of 180 g. of the crude m-trifluoromethylphenyl phosphorodichloridate, boiling below C./ 17 mm., which had been obtained by refluxing phosphoryl chloride with m-trifluoromethylphenol and distilling the reaction product, 539 g. (3.5 mole) of phosphoryl chloride and 1000 g. (6.18 moles) of m-trifluoromethylphenol was heated to reflux within a period of 20 hours, at the end of which time the temperature was 230 C. Distillation of the resulting reaction mixture gave 814.2 g. of his(m-trifiuoromethylphenol) phosphorochloridate, B.P. 195 C./20 mm.

To 101.1 g. (0.25 mole) of the above-prepared bis(rntrifluorornethylphenyl)phosphorochloridate dissolved in 50 ml. of ether was added dropwise to a solution of 50 g. (0.595 mole) of 3-(methylamino)propionitrile in 1 liter over a 22-hour period. The temperature rose to 31 C. during the addition. The whole was heated at reflux for 3 hours and then allowed to cool to room temperature. The solid which had formed was washed out with water and the resulting organic phase was separated and washed successively with dilute hydrochloric acid, aqueous sodium carbonate solution, and finally with water until neutral. The washed organic material was then dried over magnesium sulfate and filtered. Distillation of the filtrate gave 99.7 g. (94% theoretical yield) of the substantially pure bis(m-trifluoromethylphenyl) N-(Z-cyanoethyD-N- methylphosphoramidate, B.P. 173 C./ 0.07-0.08 mm. 11 1.4758-9.

P nuclear magnetic resonance analysis was consistent with the structure and showed no impurities.

The compound had a kinematic viscosity of 101.1 centistokes at 100 F. and 6.45 centistokes at 210 F.

The autogenous ignition temperature was 1070 F. for 0.07 ml. with a lag of 7 seconds. In the molten metal test it did not ignite without application of a spark, and then the flame was self-extinguishing. The flash point was found to be 518 F. and no fire point was observed at the maximum test temperature of 716 F.

Example 2 A mixture consisting of 464 g. (2.0 mole) of 2,2,3,3, 4,4,5,5-octafluoropentanol, 168.5 g. (1.1 moles) of phosphoryl chloride and about 1 ml. of dry pyridine was heated to a maximum temperature of 161 C. over a period of 9 hours. Distillation of the resulting reaction mixture gave 333.5 g. of the substantially pure bis(2,2,3,3,4,4, 5,S-octafluoropentyl)phosphorochloridate, B.P. 154C./ 15 mm.

To a solution of 21 g. (0.25 mole) of 3-(methylamino) propionitrile in 150 ml. of ether there was added dropwise, over a 1-hour period, a solution of 60 g. (0.11 mole) of the above-prepared bis(2,2,3,3,4,4,5,5-octafluoropentyl)phosphorochloridate. The temperature of the reaction mixture rose to 34 C. during the addition. The Whole was heated at reflux, with stirring, for one hour. After being allowed to cool to room temperature, the reaction mixture was washed successively with water, dilute hydrochloric acid, aqueous sodium carbonate solution, and finally with water until neutral. The resulting organic phase was dried over magnesium sulfate, and filtered. Most of the ether was evaporated from the filtrate under vacuum on the steam bath. The residue was distilled to give 46.8 g. (65.8% theoretical yield) of the substantially pure bis(2,2,3,3,4,4,5,5-octafluor-opentyl) N-(2- cyanoethyl)-N-methylphosphoroamidate, B.P. 161 C./ 0.15 mm. 11 1.36701.

The compound had a pour point of minus 30 F. and the following kinematic viscosities at the temperatures shown below.

Temp., F.: Centistokes 25 1958 The autogenous ignition temperature was 875 F., and the flash point was 478 F., and no fire point was observed at the maximum test temperature of 599 F.

Example 3 A mixture consisting of 169 g. (1.1 moles) of phosphoryl chloride and 320 g. (1.6 moles) of 2,2,3,3,4,4,4- heptafluorobutanol was refluxed for 11 hours, and the resulting reaction mixture was distilled to give 135.5 g. of the substantially pure bis(2,2,3,3,4,4,4-heptafluorobutyl) phosphorochloridate, B.P. 109110 C./25 mm. 11 1.3234-5.

To a solution of 66 g. (0.8 mole) of 3-methylaminopropionitrile in ml. of ether there was gradually added 175 g. (0.39 mole) of the above prepared bis-(2,2,3,3,4, 4,4-heptafluorobutyl)phosphorochloridate while maintaining the temperature of the reaction mixture at 0-10 C. The whole was then allowed to warm to room temperature and then distilled to give a fraction, B.P. 79102 I C./ 0.01-0.09 mm. which upon redistillation gave the substantially pure 'bis(2,2,3,3,4,4,4-heptafluorobutyl) N-(2- cyanoethyl)-N-methylphosphoramidate, B.P. 9395 C./ 0.10.3 mm. 12 1.3520, and analyzing as follows:

Calcd f0]: C H F N O P. C, H, F, 50.36%. Found: C, 27.20%; H, 2.17%; F, 50.06%.

The compound had a pour point of minus 40 F. (supercooled). The following kinematic viscosities were determined at the temperature shown below:

Example 4 2,2,3,3,4,4,5,5,6,6,7,7 dodecafluoroheptyl phenyl phosphorochloridate was prepared by heating a mixture of 133 g. (0.4 mole) of 2,2,3,3,4,4,5,5,6,6,7,7 dodecafluoroheptanol and 169 g. (0.8 mole) of phenyl phosphorodichloridate for 2.5 hours at 130 C., allowing the reaction mixture to stand overnight, adding a few drops of tributylamine, heating for 4 hours at 175 C. and finally distilling to obtain the substantially pure 2,2,3,3,- 4,4,5,5,6,6,7,7 dodecafluoroheptyl phenyl phosphorochloridate, B.P. 102-3 C./ 0.03 mm.

It was converted to the cyanoethylphosphoramidate as follows: The compound, (142 g., 0.28 moles) was added, dropwise in a nitrogen atmosphere, to a mixture consisting of 24 g. (0.28 mole) of 3 (methylamino) propionitrile and 57 g. (0.31 mole) of tributylamine over a period of about 45 minutes. The reaction was exothermic, the temperature rising to about 60 C. during the addition. Heat was then applied, and the reaction mixture was heated at 75 C. for 1.5 hours. At the end of that time, 200 ml. of chloroform was added, and the whole was allowed to stand at room temperature for about a day. After washing with ice cold, dilute hydrochloric acid and then with ice cold, dilute, aqueous sodium carbonate, the organic material was dried over anhydrous sodium sulfate. Chloroform was removed from the dried product by evaporation, the residue was filtered through sodium sulfate and Attapulgus clay, and the filtrate was distilled to give 118.6 g. (76.5% theoretical yield) of the substantially pure 2,2,3,3,4,4,5,5,6,6,7,7 dodecafluoroheptyl phenyl N (2 cyanoethyl) N methylphosphoramidate, B.P. C./0.15 mm. Redistillation after filtering through Attapulgus clay gave the purer compound, B.P. 163 C./0.05 mm.--170 C./0.15 mm, 12 1.4179, and analyzing as follows:

Calcd for C H F N O P. C, H, P, 5.59%. Found: C, 36.66%; H, 2.90%; P, 5.43%.

Nuclear magnetic resonance P analysis using phosphoric acid as standard showed a chemical shift at 4.8 p.p.m., which is consistent with the structure. Nuclear magnetic resonance H analysis in carbon tetrachloride as solvent and using tctramethylsilane as standard also confirmed the structure.

The compound had a pour point of minus 5 F., and

the following kinematic viscosities were determined at the temperatures shown below:

Temp, F.: Centistokes 25 4,984 100 101.0 210 7.25

Example m-Trifluoromethylphenyl phosphorodichloridate was prepared by refluxing (235 C., maximum) for 24 hours a mixture consisting of 533 g. (3.5 moles) of phosphoryl chloride and 1000 g. (6.2 moles) of m-trifiuoromethylphenol and distilling the resulting reaction mixture to give 230 g. of the substantially pure m-trifluoromethylphenyl phosphorodichloridate, B.P. 125-127 C./ 21 mm., n 1.4668.

To the 230 g. (0.87 mole) of the above phosphorodichloridate there was added portionwise 146.6 g. (0.44 mole) of 2,2,3,3,4,4,5,5,6,6,7,7 dodecafluoroheptanol at 100-130 C. and the whole was then heated, with stirring at 130 C. for about 4 hours. Distillation of the resulting reaction mixture gave the substantially pure 2,2,- 3,3,4,4,5,5,6,6,7,7 dodecafluoroheptyl m-trifluoromethylphenyl phosphorochloridate, B.P. 157 C./5 mm.

To a mixture consisting of 25.0 g. (0.298 mole) of 3 (methylamino)propionitrile and 30 g. (0.297 mole) of tn'ethylamine in 300 ml. of ether there was added, dropwise over a 1.5 hour period, 135.6 g. (0.236'mole) of the above prepared 2,2,3,3,4,4,5,5,6,6,7,7 dodecafluoroheptyl m trifluoromethylphenyl phosphorochloridate while maintaining the temperature'of the reaction mixture at 5 C. After all of the phosphorochloridate had been added, the mixture was refluxed (35 C.) for an hour. The by-product triethylamine hydrochloride was filtered oil, and the residue was washed successively with water, dilute hydrochloric acid, water, dilute aqueous sodium carbonate solution and finally with salt water until neutral. The resulting organic phase was then dried over Drierite and filtered. Ether was stripped from the filtrate and the residue was distilled to give a fraction BR 165 l67 C./0.02 mm., which upon redistillation gave 108.7 g. of the substantially pure 2,2,3,3,4,4,5,5,6,6,- 7,7 dodecafluoroheptyl m trifluoromethylphenyl N (2- cyanoethyl) N methylphosphoramidate, RI. 160- 165 C./0.010.02 mm., n 1.4042, and analyzing as follows:

CalCd for C13H14F1503N2P. C, H, P, 4.98%. Found: C, 34.53%; H, 2.19%; P, 4.76%.

The compound was found to have a pour point of minus 5 C., and the following kinematic viscosities were determined at the temperatures shown below:

Temp, F.: Centistokes 25 5,759 100 109.1 210 7.52

The autogenous ignition temperature was found to be 1005 F. for 0.04 ml. with a lag of 7 seconds. The flash point was 511 F., and no fire point was observed at the maximum test temperature of 622 F.

The operative fluid of the present hydraulic systems and methods may be a mixture of one or more of the present N-alkyl N (cyanoalkyl)phosphoramidates. In some instances, it will be found that those of the compounds having metaand/or ortho-substitution at the phenyl nucleus possess better fluidity than do the parasubstituted compounds. The presently provided phosphoramidates may also be mixed with known hydraulic fluids, e.g. the trialkyl phosphates or the dialkyl arylphospho- 10 nates or the aromatic polyethers, so long as the properties of the resulting mixture meet the specifications required of a hydraulic fluid for the intended use. Obviously, if the intended use places no limitation on such factors as either lowor high-temperature behavior, or if no fire-hazard exists, the said phosphoramidates may be present in any proportion. However, if one or more of these factors s important, then care should be observed in preventing an undesired extent of dilution. Generally, at least a major component of the mixture should be the fluorine-substituted diorgano N alkyl-N-(cyanoalkyl)phosphoramidate.

Also, the usual fluid additives, e.g., corrosion inhibitors, antioxidants, viscosity-index improvers, etc., may be added to the presently provided fluid phosphoramidates, although for most purposes it will be found that such additives can be dispensed with.

It is to be understood that although the invention has been described with specific reference to particular embodiments thereof, it is not to be so limited since changes and alterations therein may be made which are within the full intended scope of this invention as defined by the appended claims.

What we claim is:

1. The compound of the formula in which R is selected from the class consisting of fluorinesubstituted alkyl radicals of the formula wherein A is selected from the class consisting of hydrogen and fluorine, m is 0 to 7 and n is 1 to 4, and perfluoroalkylphenyl radicals of from 7 to 10 carbon atoms, R is selected from the class consisting of R and aromatic hydrocarbon radicals which are free of olefinic and acetylenic unsaturation and contain from 6 to 12 carbon atoms, Y is an alkyl radical of from 1 to 4 carbon atoms, and T is a bivalent alkylene radical of from 1 to 4 carbon atoms.

2. The compound defined in claim 1, further limited in that each of R and R is a (perfluoroalkyl)phenyl radical of from 7 to 10 carbon atoms.

3. The compound defined in claim 1, further limited in that each of R and R is a fluorine-substituted alkyl radical of the formula radical wherein A is selected from the class consisting of hydrogen and fluorine, m is 0 to 7 and n is 1 to 4.

4. The compound defined in claim 1, further limited in that R is a fluorine-substituted alkyl radical of the formula where m is 0 to 7 and n is l to 4, and R is a perfluoroalkylphenyl radical of from 7 to 10 carbon atoms.

5. The compound defined in claim 1, further limited in tha; R is'a fluorine-substituted alkyl radical of the formu a where m is 0 to 7 and n is 1 to 4, and R' is an aromatic hydrocarbon radical which is free of olefinic and acetylenic unsaturation and contains from 6 to 12 carbon atoms.

6. Bis(m-trifluoromethylphenyl) N-(2-cyanoethyl)-N- methylphosphoramidate.

7. Bis(2,2,3,3,4,4,5,5-octafiuoropenty1) N-(Z-cyanoethyl -N-methy1pho sphoramidate.

8. Bis(2,2,3,3,4,4,4-heptafluorobutyl) N-(Z-cyanoethyl)-N-methylphosphoramidate.

9. 2,2,3,3,4,4,5,5,6,6,7,7-dodecafiu0roheptyl phenyl N- (Z-cyanoethyl)-N-methyl phosphoramidate.

10. 2,2,3,3,4,4,5,5,6,6,7,7-d0decafiuoroheptyl m-trifiuoromethylphenyl N-(Z-cyanoethyl) N methylphosphoramidate.

1 2 References Cited UNITED STATES PATENTS 2,574,516 11/1951 Walter et a1. 260984 X 2,852,550 9/1958 Godfrey 260-984 2,995,596 8/1961 Debo 260-984 CHARLES B. PARKER, Primazy Examiner.

A. H. SUTTO, Assistant Examiner. 

